An active matrix LCD device has the advantages of portability, low power consumption, and low radiation, and has been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras and the like. Furthermore, the active matrix LCD device is considered by many to have the potential to completely replace CRT (cathode ray tube) monitors and televisions.
FIG. 4 is an abbreviated block diagram of certain parts of a typical active matrix LCD. The LCD 100 includes a liquid crystal (LC) panel 140, a gate driving circuit 130, a data driving circuit 120, and a timing control circuit 110, a power supply 150, and a backlight circuit 170. The backlight circuit 170 drives a light source to emit light beams for illuminating the LC panel 140. The timing control circuit 110 is used to control the gate driving circuit 130 and the data driving circuit 120. The gate driving circuit 130 provides a plurality of scanning signals to the LC panel 140. The data driving circuit 120 provides a plurality of gradation voltages to the LC panel 140 when the LC panel 140 is scanned.
However, the LCD 100 can not automatically adjust the brightness when the ambient brightness is changed. Thus a user may find that his or her eyes easily become tired.
What is needed, therefore, is an LCD that can overcome the above-described deficiency.